1. The Field of the Invention
The present invention relates to improvements for disc players and in particular, to an improved body design for the disc player.
2. The Relevant Technology
In the following specification the term disc player will be used to refer to compact disc players, recordable compact disc players (CDR), re-writable compact disc players (CDRW) and DVD players, both portable and fixed, all of which are suitable for incorporating the disclosed inventions.
The prior art teaches of disc players that comprise disc enclosures and separate chassis employed to mount a spindle motor and an optical pick-up unit (OPU). Mounting the spindle motor and OPU on a chassis provides a method for controlling the position of the OPU with respect to a rotating disc.
An inherent problem of such chassis is that they are prone to transmit vibrations to the rest of the disc player. These vibrations result from the excitation caused by the disc rotation. The chassis are also subject to disturbances themselves from external vibrations, which can affect the overall performance of the disc player.
To overcome problematic features of such internal and external vibrations the chassis is normally connected to the disc enclosure via rubber anti-vibration (AV) mounts. These AV mounts are additional components that require the development of mould tools in order to provide for their manufacture, as well as their specific construction and incorporation within the assembly procedure. Such procedures add significant cost to the manufacture process, thus resulting in additional costs being passed onto the consumer.
A further problematic design feature also results from employing a separate chassis and disc enclosure. Due to tolerance levels required in separately manufacturing such components the clearance between the disc and the inner surface of the disc enclosure must be maintained at a minimum value. This significantly hinders the overall miniaturization of such disc players. In addition, wind drag resulting between the spinning disc and the disc enclosure is directionally proportional to the dimensions of the disc enclosure. Therefore the smaller the disc enclosure, the smaller the wind drag. A small wind drag is advantageous in that the current required to drive the spindle motor is reduced. This has particular relevance for portable disc drives that draw current from a battery, as the level of current drawn affects the battery lifetime.
A further problematic design feature taught in the prior art relates to the securing of the disc enclosure. Such securing means, employ latches that lock when the lid of the enclosure is closed. In order to gain access to the disc enclosure, for the placing or removing of a disc, requires the operator to manually overcome the latch.
Within such systems the manual opening of the disc player is not related to the rotation of the disc. Therefore, if the lid is inadvertently opened when the disc player is writing data to a disc the laser safety cut off will immediately stop the write action. Written data will therefore not end by the correct closing procedure for the writing session. Without proper closure of the session the data just written, and all other data on the disc, will not be accessible at a later date and so is effectively lost.
In addition, if the user has access to the disc while it is spinning at high speed there is a risk of personal injury if the user were to touch the edge of the disc. A point to note is that this is not such a problematic feature in traditional portable CD players where the discs spin at 15 Hz however it does become a concern in relation to CDRWs where discs can be driven at up to 120 Hz. It is also possible that a user's hand acting as a break on the spinning disc could cause damage to the spindle motor.
In order to overcome some of these problematic features, the prior art teaches of disc players which incorporate a disc brake employed to stop the disc spinning as soon as the lid is opened. However, these brakes can produce debris and contamination as they come into contact with the disc. They also make placement of the disc on the spindle motor more difficult as the break is required to be moved aside before the disc is deployed.
CDRW or CDR players which employ manually operated lids may also employ write locks to prevent the lid being inadvertently opened. However, these write locks require their own motors, solenoids and gear mechanisms in order to activate the locks when the lid is closed.